The objective of this Children's Cancer Group clinical trial is to determine the maximum tolerable dose of cisplatin, given as a six-hour infusion, which can be given with topotecan as a continuous infusion; to determine the toxicities of the combination of topotecan and cisplatin; and to determine the pharmacokinetics of topotecan and cisplatin. Treatment will consist of cisplatin given as a 6 hour infusion followed by topotecan as a 72 hour continuous infusion.